Chromatography is one of the most widely used techniques for chemical analysis. The chromatographic process has been around for over a century, while commercial instruments for chromatography have been available since the 1950s. One of the drawbacks in the current art of chromatography is that unlike other chemical analysis techniques (spectroscopy, chemical sensors, etc.), chromatography cannot be performed continuously. In the current art, a specific volume of chemical sample is passed through a chromatographic medium such as a column or cavity, and the output of the sample after passage through the medium, recorded over time, is the resulting chromatogram. Under these conditions, a second sample is not introduced to the chromatographic medium until the first sample has completely passed through the column. Often, the medium is then flushed with gas or liquid before a second, new sample is introduced. Accordingly, it can require a few minutes to several hours between consecutive samples on the same chromatography apparatus.
There have been several attempts to develop continuous chromatographic methods. The most common technique is to stagger or separate sample introduction by a known time-delay, using the traditional injection method used in chromatography, such that a series of staggered chromatographs with a similar time delay will be output with known time delays. A second method involves passing the chromatographic medium, such as the column, through a continuous gas. Previous patents for continuous chromatographic systems include the following:
U.S. Pat. Nos. 5,578,111 and 5,770,087 teach a chromatographic process in which the mixture's components can be dissolved and/or dispersed and/or evaporated, while the phases containing the sorption agents move in opposing directions, and the separated components of the mixture held on the sorption agents are recovered after passage through the separation path.
U.S. Pat. No. 7,749,390 B2 teaches a quasi-continuous process for separating binary and multi-substance mixtures by introducing a sample to a unit which consists of a plurality of individual columns bonded to one another in a direction X in a circle, after which the eluents from the respective columns can be discharged from the respective portion of the circle.
U.S. Pat. No. 5,922,106 A teaches a chromatographic process in which small liquid volume of flow from a liquid process stream containing organic compounds is diverted by an automated process to a heated vaporization capillary where the liquid volume is vaporized to a gas that flows to an automated gas chromatograph separation column to chromatographically separate the organic compounds.
U.S. Pat. No. 5,827,945 A teaches a gas flow distribution system accumulates a sample from a sample bearing carrier gas in a micro-accumulator, delivers it using a carrier gas to a gas chromatography column, and supplies a carrier gas to the gas chromatography column to facilitate separation of the sample into sample components and transport the sample components to a mass spectrometer for trace vapor detection and analysis or testing in real time.
U.S. Pat. No. 3,136,616 teaches a chromatographic system that comprises continuously feeding a material having a plurality of components to be separated and a carrier fluid in a period composition wave of constant frequency to the inlet of a chromatographic column, whereby the said components travel through the column in respective waves at different rates, and emerge from the column out of phase with each other.
U.S. Pat. No. 3,345,858 teaches a chromatographic system in which a carrier gas is passed continually through a column that has been pre-saturated with n-paraffin content, which fixed column samples of the analysis mixture are periodically injection into the carrier gas stream.